Projectiles launched from platforms of different elevation.

1."A ball is kicked from a platform 3.2m above the ground at an angle of 20 degrees above the horizontal. If the ball lands on the ground 100m away, what is the initial velocity of the ball?" There is no air resistance acting upon the ball and we have to use constant acceleration equations.

2. v = vo + at
x = xo + vo t + ½ a t^2
v^2 = vo^2 + 2a(x - xo)

3. The farthest that Ive been able to get is that it is between 35 and 40 but that is only by guess and check which is not an acceptable method. Any input helps. Thanks!